Concerns about the continuing efficacy of heartworm preventives have led to responses from the American Heartworm Society and Companion Animal Parasite Council.
The Companion Animal Parasite Council issued a statement in late May noting that reports of resistance appear to be coming from cases of heartworm infection involving dogs in the south-central United States.
"However, because it is clear that the vast majority of heartworm-positive dogs result from failure of compliance rather than product resistance, veterinarians should continue to recommend the use of year-round heartworm preventives as the best way to prevent infections," according to the statement. "Veterinarians should also continue to emphasize the need for heartworm diagnostic tests at recommended intervals and appropriate times."
The American Heartworm Society has assembled a commission to publish recommendations for development of protocols for heartworm preventives to minimize the potential for resistance.
The move follows the society's 13th triennial symposium, April 16-17 in Memphis, which included a session on evidence for possible selection of heartworms resistant to preventives.
Other sessions during the symposium focused on the worldwide spread of heartworm disease, emerging issues in heartworm infection and relevant diseases, new strategies for prevention and compliance, heartworm infection in cats, and diagnosis and treatment strategies for heartworm infection.
Researchers presented findings suggesting the impending arrival in the United States of the lungworm Angiostrongylus vasorum, currently endemic in Europe and northeastern Canada, and the probable arrival in North America at some point of the heartworm Dirofilaria repens from Europe and Asia.
An executive summary of the symposium is available at www.heartwormsociety.org/AHS-Executive-Summary.pdf. The society plans to post recommendations for development of protocols to minimize resistance at www.heartwormsociety.org after adoption by the board of directors.
The AVMA also offers informational resources regarding heartworm disease. AVMA Collections—the open-access, online monograph series—recently released a compilation of JAVMA and AJVR scientific articles relevant to heartworm disease at www.avma.org/avmacollections/heartworm/.
The AVMA also offers client brochures on heartworm disease at www.avma.org/products/client/heartworm.asp. The brochures are free to download and available by order in print in packages of 50.